Absorption refrigeration unit with a centrifugal separator



Sept. 21, 1954 E, p, wHn-Low 2,689,466

ABSORPTION REFRIGERATION UNIT WITH A CENTRIFUGAL SEPARATOR @Array/wy Sept. 21, 1954 E. P. wHlTLow 2,689,466

ABSORPTION REFRIGERATION UNIT WITH A CENTRIFUGAI.. SEPARATOR Filed June so, 1951 s sheets-sheet 2 Marra/mex Sept. 21, 1954 E. P. wHgTLow 2,689,466

ABsoRPTIoN REFRIGERATION UNIT WITH A CENTRIFUGAL sEPARAToR Filed June 5o, 1951 s sheets-sheet s l; A 0000000900 ,f Hummm@ .4B-l

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a Hrm/wir Patented Sept. 2l, 1954 ABSORPTION REFRIGERATION UNIT WITH A CENTRIFUGAL SEPARATOR Eugene P. Whitlow,

Servel, Inc., New Delaware Evansville, Ind., assignor to York, N. Y., a corporation oi Application June 30, 1951, Serial No. 234,525

11 claims. 1

'I'he present invention relates to refrigeration and more particularly to a self-contained absorption type refrigeration unit.

Relatively small self-contained vacuum type absorption refrigeration units of up to five-tons ice melting capacity a day have been extensively used for air conditioning. In such units the refrigerant is evaporated at the interior of a finned coil and the air to be cooled passes over the exterior of the coil and between the fins. In units of larger capacity such a direct `expansion evaporator is impractical in a self-contained unit because it increases the size and weight of the unit to such a degree as to prevent it from being transported through door openings of usual dimensions and presents a problem of air distribution. Furthermore, in such units of larger capacity the separation of liquidabsorbent from vapor and the cooling of the larger volume of liquid refrigerant present additional problems. One of the objects of the present invention is to provide a novel construction andarrangement of elements to provide alself-containedvacuum type absorption refrigeration unit of relatively large capacity which is adapted to be transported through conventional door openings.

Another object is to provide a vacuum type absorption refrigeration unit in which a primary refrigerant is utilized to cool a secondary refrigerant which, in turn, is used to cool the air to provide a more compact construction and `a greater flexibility of installation.

Another object is to provide a vacuum type absorption refrigeration apparatus of the type indicated with a centrifugal separator for directing expelledlvapor in a'circular path at" high velocity to separate liquid therefrom by centrifugal force. y

Another object is to provide a vacuum type absorption refrigeration apparatus with a flash chamber for cooling liquid refrigerant from the condenser to the evaporator temperature before it is introduced into the latter by evaporating a portion of the refrigerant and utilizing the vacuum of the system to insulate the flash chamber from the ambient.

These and other objects will become more apparentA from the following description and drawings in which like reference Vcharacters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and not a definition of the limits of the invention, reference being had for this purpose to the appended claims. In the drawings:

Fig. l is a side elevational view of a self-contained vacuum type absorption refrigeration unit and showing the `construction and arrangement of the parts-thereof;

Fig. 2 is a top plan view of the apparatus showing the centrifugal separator and insulated flash chamber and showing their relationship to the other elements of the unit;

Fig. 3 is an end elevational view of the left hand end of the apparatus as viewed in Fig. 1;

Fig. 4 is an end elevational View of the right hand end of the apparatus as viewed in Fig. l;

Fig. 5 is a transverse sectional View of the centrifugal separator taken on line 5-5 of Fig. 2 and showing a plurality of discs arranged in a cylindrical casing to provide helical paths therein;

Fig. 6 is a front View of one of the discs;

Fig. '7 is a side elevational View of a disc showing the blades twisted at an angle to the plane of the disc; and

Fig. 8 is a sectional end view of the combined evaporator and absorber and showing the banks of tubes constituting a centrally located evaporator with absorber sections at each side.

One of the features of the invention is the construction and arrangement of elements to provide a self-contained vacuum type absorption refrigeration unit. The unit comprises a frame I0 having a rectangular base I I formed by angle irons welded at the corners. Angle iron stanchions I2 and I3 project upwardly from the corners at one end of the base and have a saddle I4 at their upper ends, see Fig. 4. Another pair of stanchions I5 and I6 project upwardly from the side rails of the base II intermediate their ends and have a saddle I'l at their upper ends. Crossstruts I8 and I9 extend between the stanchions I2 and I5 and similar cross-struts I8' and I9' extend between the stanchions I3 and I6. A cylindrical shell 20 enclosing the combined evaporator and absorber, later to be explained in detail, is mounted on the saddles I4 and Il.

The cylindrical shell 20 has spaced brackets 2l on the top thereof at one side of the center for mounting a condenser 22 which extends longitudinally of the shell. A centrifugal separator 23 is located at the top of the cylindrical shell 2U at the opposite side of its center from the condenser 22. At the rear of the centrifugal separator 23 is a combined iiash chamber and gas storage Vessel 24 also extending longitudinally of the shell and supported in position thereon by its connections with the shell.

`A liquid heat exchanger 25 is located below the cylindrical shell 29, between the upright stanchions I2, I3, and I5, I6 and is supported at one end by a bracket 26 between the cross-struts I3 and I8 and at its opposite end by a bracket 2'? between the stanchions I and I5. The liquid heat exchanger is inclined at an acute angle to the horizontal' adjacent thebase IlI and? locate below the shell 26 a distance sufficient to provide a liquid column of solution therebetween of a height to balance the difference in pressure be tween the high and low pressure sides of thev system.

Mounted on the base II beyond the stanchions I5 and I6 is a combined generator and' vapor liquid-lift 28 which extends upwardly above the cylindrical shell 29 at one end thereof. The upper end of the lift 28 is connectedto one end of the centrifugal separator 23 tangentially thereof, see Fig. 3, and the opposite end of the latter is connected to thecondenser 22 by a vapor pipe 29, see Fig. 2, which support it above the cylinder shell. A. horizontally" arranged cylin drical leveling vessel 39v is located between the vapor liquid-lift 28 and the liquidzheatf exchanger 25 and is supported byV brackets SI projecting from the stanchions I5 and I6. The elements are connected by suitable conduits to provide circuits for the refrigerant and absorbent. andthe conduits are supported. by the various elements to provide a self-contained unit. It will be noted by reference to Figs. 3 and 4 that all of the elements are confined within the lateral dimensions of the stanchions- I5 and I5 and thatl all of the elements are located between the base II and top of the condenser 22. These dimensions are less' thanv the usual door-opening sizes so that the unit may be transported through such open;- ings to the location where itA to be used.V For example, a self-contained vacuum type absorption refrigeration system of twenty-five tons ice melting capacity per day utilizing water as a refrigerant and a lithium bromide solution, as. an absorbent and constructed and arranged; as de'- scribed above has a width of 3o inches, a height of 83 inches and a length of 89` inches.

The combined generator and` vapor liquid-lift 2'8 isY described and claimed in an application for United States Letters Patent ofl Walter M. Simpson Serial No. 219,777', nled April 7:, 1951. Suce it to state herein that the combined generator and vapor liquidi-lift comprises a. lower portion 32v providing an extended heating surface, see Fig. 2, and an upper tapered lift portion- 33'. The lower portion 32 and lift portion 33 are enclosed in a 'jacket 34 throughout their length and the jacket is provided with a steam inlet port 35, a vent pipe 36l adjacent its upper end and a condensate drain 37 at its lowerl end.

The'centrifugal separator 23 comprises a cylindrical casing having means therein for directing vapor in a helical path at high velocity, as later explained in detail. The condenser 22 comprises a shell with headers 39 and 49 at each end and tubes 4I extending through the shell and into the headers. The bottom of the condenser 22 is connected to the combined flash chamber and gas storage vessel 2li by a U-shaped conduit 42. The combined flash chamber and. gas storage vessel 24 comprises an inner flash chamber 43 and an enclosing jacket 45, as later explained. in detail, and the inner chamber 53 is connected to the shell 20 by an insulated conduit l5 for delivering liquid refrigerant to the evaporator.

Liquid absorbent is delivered from the casing of the centrifugal Separator 23 to the absorber in shell 20 in a path of now including conduit 46, inner passages 41 of the liquid heat exchanger 25, conduit 48 and T-shaped manifold 49, see Figs. 1 and 3. Absorbent liquid strong in refrigerant is delivered from the shell 20 to the base of the combined generator and vapor liquid-lift 28 in a. pathV of yflow including conduit 56; outer passages 5I of liquid heat exchanger.'v 25, conduit 52, leveling vessel 30 and conduit 53.

The combined evaporator and absorber is de* scribed. and claimed in an application for United States Letters Patent of Lowell McNeely filed concurrently therewith. As shown in Fig. 8, the evaporator comprises a bank 54 of tubes 55 ar-l ranged' one over the other in vertical rows from the top to the bottom of the bank. Groups of the tubes each of the rows are connected at alternate ends to provide a plurality of vertically aligned serpentine coils in each row and the ends 0f the corresponding coils in the plurality of rows are connected by headers 56 and 5l to provide individual secti0ns58. Headers 56 are connected by conduits 59 to an upright inlet manifold 69 and. headers 5T are connected by conduits 6| to an upright outlet manifold 62, see Fig. fl, so that a secondary refrigerant to be cooled may flow concurrently through the sections 58 in parallel to reduce the pressure drop in the evaporator. Overlying the-top of the bank 54 of tubes 55 constituting the evaporator is aliquid distributor 63 having a plurality ofA parallel troughs 64. The parallel troughs are so arranged as to provide a sidewall 65 overlying eachA vertical row of tubes 55 and each wall is provided With aV capillary feeding means 66 for delivering liquidrefrigerant onto the uppermost tube of each row as illustrated and described in detail in the McNeely application.

The absorber comprises banks 61 and. 58 of tubes 69.- on either side of the bank of tubes 55 constituting the evaporator. The tubes 69 are arranged one over the other in vertical lrows from the. top to the bottom of the bank and the tubes of each row are connected alternately at opposite ends to provide a plurality of vertical serpentine coils arranged in parallel. A liquid distributing means 63 likethat described for the evaporator overlies each of the banks 6l and 68 of absorber tubes 69- fo-r distributing absorbent for gravity flow over each coil and asorbent is suppliedto each distributing means by conduit 46 and manifold 49. The ends of -the coils of each bank are connected by headers .1.0 and 'Il which, in turn, are connected to horizontal manifoldsV 'I2 and 13V, see Figs. 1 and 3. Manifold I2 may be connected to any source of cooling water supply such as a cooling` tower or water main and manifold 'I3 is connected to the header 39 of condenser 22. The banks 54, 6.1 and 68 of tubes 55 and 69 constituting the evaporator and absorber sections are supported in the cylindrical shell 20 by brackets 'I4 and 15.

A- purging arrangement is provided for withdrawing non-condensable gases fromthe corre bined evaporator and absorber shell 2G and comprises a vessel 76 connected to the shell through a suction tube 'il and to the conduit 48 for absorbent weak in refrigerant by av connection. '18. The purge vessel i6 constitutes an auxiliary absorber for creating a relative partial vacuum to withdraw non-condensable gases-from the shell 29. A fall tube 'i3 connects the bottom of the vessel 76 to a separating chamber 83 and a conduitt! connects the side of the separating chamber adjacentthe. top. thereof to the jacket 44 of the combined flash chamber and gas storage veissel 24. The bottom of the separating chamber 80 is connected by a conduit B2 to the line for solution strong in refrigerant flowing toward the generator 28.

Another featurei of the present invention is theV novel construction of the centrifugal separator 23 as illustrated in detail in Figs. 5, 6 and 7.` "The centrifugal separator 23 comprises a cylindrical shell 84 slightly inclined downwardly to the left as viewed in Fig. 5 with a rod 85 located axially thereof and mounting a plurality of discs 86. The discs 86 are mounted on the rod 85 at the central portion of rod 85 between conduit 46 and vapor pipe29 to provide an open swirl chamber above the lift conduit 33. As illustrated in Fig. 6, each disc 86 has a central hub 81 and a plurality of radial slots 88 forming blades 89, eight of such blades being shown in Fig. 6. The blades 89 are twisted at an acute angle to the plane of the disc 86 and the plurality of dics are so arranged on rod 85 that the leading edge 98 of each blades forms a continuation of the trailing edge Ell of a blade of the preceding disc at their outer ends. The inclined faces of the blades B9 of adjacent discs 86 will thus direct vapor through a plurality of helical paths 92 in shell 84. When discs 86 with eight blades 89 are provided,` the gas will be directed in eight helical paths 92 formed by the blades 89 and casing 84. Vapor entering the cylindrical separator casing 84 tangentially thereof is given an initial circular motion or swirl which is continued through the helical paths 92 and, due to the high velocity of the vapor flowing toward the condenser, any liquid in the vapor is thrown outwardly against the Wall of the casing by centrifugal force. The liquid flows down the sides of the casing and along the inclined bottom of the casing into the conduit 46.

Still another feature of the invention resides in the combined flash chamber and gas storage vessel 24. The inner flash chamber 43 receives liquid refrigerant from the condenser 22 through the U-tube 42 at a temperature corresponding vapor pressure in the condenser and reduces the temperature of the refrigerant tothe evaporator temperature by evaporating a portion of the refrigerant at the vapor pressure in the evaporator and absorber. Because `of the rapid boiling and. agitation of the refrigerant during flashing, such flashing is performed in the flash chamber 43 before it is introduced into the evaporator. Liquid refrigerant flows from the bottom of the` chamber 43 to the liquid distributor 63'for the bank 54 of evaporator tubes 55 through insulated liquid pipe 45 and a vapor pipe 93 extends upwardly from shell 2D through the jacket 44 and chamber 43 and terminates above the liquid level. Flashed vapor flows from chamber 43 through vapor pipe 93V into shell 20 where it is absorbed in absorption solution.

In accordance with the present construction, the jacket 44 is` connected to the refrigeration system to provide a vacuum insulating space 94 around the chamber. The apparatus is initially evacuated to the lowest pressure that can be produced by known pumps, less than 1 mm. Hg absolute, and is then charged with a water solution of lithium bromide. A pressure will exist in the space 94 corresponding to the vapor pressure of refrigerant at the temperature of the flash chamber 43, and provide a relatively low vacuum in space 94 to heat insulate the flash chamber from 6.. the ambient. Such vacuum insulation reduces the heat loss from the system and avoids condensation on the wall of chamber andi the general nuisance of such condensate dripping from the chamber over the other parts of the apparatus.

Non-condensable gases withdrawn from the shell 2U by the purging vessel 'IE are delivered by the fall tube 19 to the separating chamber 80 and as they accumulate therein they will escape through the conduit 8| into the space 94. Such gases will mix with refrigerant vapor when delivered to the vacuum space 94 and will exist therein at relative partial pressures. The gases are generated in the system at a very slow rate, probably as a result of corrosion, and will gradually increase the total pressure but not by an amount to appreciably affect the insulating quality of the space. When a sufficient amount of gas has been delivered to the space 94 to cause an appreciable increase inthe pressure, vthe gases may be withdrawn from the jacket 44 by a suitable vacuum pump through an exhaust valve 95. After the apparatus has been fabricated to provide an hermetically sealed system, evacuated to a low pressure and charged with the refrigerantabsorbent solution, it is intended to operate for a period of at least twelve years except for removing gases from jacket 44 once a year at the beginning of a cooling season. One form of the invention having now been described in detail, the mode of operation of the unit is explained as follows: p

The self-contained refrigeration unit is transported to the locationwhere it is to be used, the manifolds and 62 connected to an auxiliary cooling system containing a secondary refrigerant such as chilled water and manifold 12 is connected to a supply of cooling water such as a cooling tower. It will be understood that the secondary refrigerant in the auxiliary cooling system, not shown, will be circulated through the evaporator tubes 55 and one or a plurality of heat exchange elements in the enclosures to be cooled and that cooling water will be circulated through the absorber tubes 69 and condenser 22.

To initiate operation of the apparatus steam is supplied to the combined generator and vapor liquid-lift 28 through the conduit 35 and the steam is maintained at atmospheric pressure in the jacket 34 by the vent pipe 36. The heat of `the steam is transferred through the extended wall surface of the lower portion`32 and through the wall of the lift tube 33 to the solution. therein to expel refrigerant vapor therefrom. Due to the correlation of the rate of vapor generation. to the cross-sectional area of the lift conduit 33 the vapor will flow upwardly through the lift conduit at high velocity and lift absorption solution at a controlled rate of `relative circulation. For example, each pound` of refrigerant vapor expelled will liftfourteen pounds of solution to the centrifugal separator 23. y

Due to the tremendous volume of the expelled vapor at the low pressure existing in the apparatus the vaporflows at very high velocity from the upper end of lift conduit 33 toward the condenser 22, As the vaporenters the cylindrical casing 84 of the centrifugal separator 23 tangentially thereof, see Figs. 3 and 5, it is given an initial circular swirling motion which causes `most of the liquid absorbent to be thrown :against the wall of the casing by centrifugal force. As the vapor `continues its flow toward condenser 7. 22- athigh velocity it is directed by the discs 86, see: Fig., through the helical passages. 92 toA continue its circular motion. Any liquid absorb-` ent remaining in the vapor is thrownl outwardiy by centrifugal force against the wall of casing' 84. The expelled liquid flows down the sides and alongl the inclinedA bottom of casing 84 and into the conduit 46. It has been found that with suona centrifugal separator 23 as shown in Fig. 5 all of the absorption solution is removed from the vapor and due to the spacing between the outer edges of successive blades 89 of the disc 86 the liquid flows by gravity into the conduit 4B. The vapor continues its flow from the casing 84 of the centrifugal separator 23 through the vapor pipe 29 into the condenser 22 where it is condensed to a liquid.

Absorbent solution weak in refrigerant flows by gravity fromy the centrifugal separator 23 to the liquid distributing means 63 for the banks 6l and 68 of absorber tubes 69 in a path of ow comprising the conduit 46, inner passages 41 of liquid heat exchanger 25, conduit 48 and manifold 49.. The liquid absorbent is uniformly distributed along the uppermost tube S9 of each vertical row of tubes in banks 51 and 68 and drips from each tube to the next lowermost from the top to the bottom of the rows of tubes. The liquid absorbent flowing over the tubes in thin lms provides an extensive surface of absorption4 solution and, due to its affinity for refrigerant, it absorbs refrigerant vapor as fast as it is formed. Absorption solution, strong in refrigerant, ows from the bottom of shell 28 to the lower end. of portion 32 of combined generator and vapor liquid-lift 28 in a path of flow comprising conduit 59, outer passages 5l of liquid heat exchanger 25, conduit 52, leveling vessel 3D and conduit 53 to complete a cycle of operation. The absorption of refrigerant vapor produces a low pressure in the cylindrical shell 28, for example, 7mm. Hg absolute, at which pressure the refrigerant, water, will evaporate at 43 F.to produce a refrigerating effect.

The differencev in pressure between the condenser 22 and shell 20 is maintained by a column of liquid refrigerant in the U-tube 42 and the difference in. pressure between thev cylindrical shell. and the combined generator and vapor liquid-lift 28 is maintained by columns of liquid absorbent in the conduits 48 and 50. For example, the liquid will stand at some level a: in the U-tube 42,. see Fig. 1, at a level y in conduit 46 connected to conduit 48 through the liquid heat exchanger 25, at a level c in conduit 50 and at a level' w in the leveling vessel 30.

Liquid refrigerant entering the ash chamber 43r is cooled from the temperature of the condenser 22 to the temperature of the evaporator by flashing a portion of the liquid. This flashing occurs automatically because of the reduced pressure in the cylindrical shell 20 and is in the form of a violent boiling. This violent boiling is performed. in the flash chamber 43 before the liquid refrigerant is introduced into the evaporator to prevent agitation and spilling of refrigerant therein. The liquid refrigerant flows from the fiash chamber 43 through the liquid line 45 to the liquid distributor 83 in Shell 20 which distributes it for gravity flow over the rows of evaporator tubes 55. As tubes 55 are closely vadjacent to and in open communication with the banks 61v and B8 of absorber tubes 69, the refrigeranty will evaporate at low temperature on the exterior of the tubes and cool. the secondary re- 8 frigerant flowing through the4 interior' of. the. tubes. The refrigerant vapor is absorbed in the,K absorption solution fiowing in parallel paths with the liquid refrigerant and the solution strong in. refrigerant then flows back to the base of the generator 28 as previously explained.

The iiash chamber 43 is insulated from the ambient by the jacket 44. When no gases: are present the space 94 will contain refrigerantva-y por at a. vapor pressure correspondingV to the.- temperature of the flash chamber 43 and produce a low vapor pressure or vacuumin the space. For example, with a refrigerant temperature of 43 F., a pressure of 7 mm. Hg absolute will exist in the space 94. The higher pressure inv vessel. at the lower endof the fall tube 19 will. force a column of liquid up the conduit 8| to seal thejacket from the remainder of the system.

During the operation of the system non-condensable gases will be withdrawn from the shell2 2li and transferred through the fallV tube 19.` to: the separating chamber A80. When sufficient gasaccurnulates in the separating chamber 80 to depress the liquid level below the conduit 8l, gas will escape through the conduit and into the jacket 44. Such gas will mix with the refriger- .ant vapor in space 94 and the total pressure therein will increase above the vapor pressure of the aqueous lithium bromide solution atv its concentration and temperature inconduit 8|. As the amount of gas in the jacket 44 increases it will gradually increase the pressure therein andf from timeto time, once a year or less, the gases. are withdrawn through the exhaust valve 94 by a suitable suction pump. Liquid absorbent. flows. from the vessel 88 through conduit 82, heat exchanger 25 and conduit 52 to leveling chamber 30.

It will now be observed that the present in.- vention provides a self-contained vacuum type absorption refrigeration system. of relatively large capacity having a novel construction and arrangement of elements to reduce its overall dimensions to a minimum. It will. also be observed that the present invention provides a centrifugal separator for separating liquid absorbent from refrigerant vapor by centrifugal force. It will still further be observed that the present invention provides a combined flash chamber and gas storage vessel for insulating the ash chamber from the ambient.

While a single form` of the invention is herein illustrated and described, it will be understood that modifications may be made in the construction and arrangement of elements without. departingr from the spirit or scope of the invention. Therefore, without limitation in this respect, the invention is defined by the following claims.

I claim:

1. A self-contained vacuum type absorption refrigeration apparatus comprising a frame having a base and spaced upright stanchions, a shell mounted on the stanchions above the base and having an evaporator and absorber therein, a condenser mounted on the top of the shell, a generator mounted on the base and havinga vapor liquid-lift projecting upwardly above the shell at one end thereof, av centrifugal separator having a horizontal casing connected` between the upper end of the vapor liquid-lift .and con.- denser with means therein for directing vapor in a helical path, a liquid heat exchanger mounted on the base of the frame below the shell, and conduits connecting the elements for the gravity flow of a refrigerant and absorbent raised by the vapor liquid-lift and' providing liquid columns betweenthe shell and liqudheat exchanger.

2. A, self-contained vacuum type absorption refrigeration apparatus comprising a frame having a base andspacedupright stanchions with saddles at theirv upper ends, a cylindrical shell mounted onthe saddles ,above the b ase and having brackets at its top and an `evaporator and absorber therein, a condensersupported on the brackets at the top vof the shellat one side thereof,.a. generator mountedon the base and having a vapor liquid-lift projecting upwardly above the shell at one end thereof. a horizontal separating chamber connected between the upper end of the vapor liquid-lift and `condenser and supported thereby at the side of the` shell opposite, the condenser, a flash chamber mounted on the top of 1 the shell at one endl of thel separating chamber, a liquid heat exchangermounted on the base of the frame between the upright stanchions, and conduits connecting the elements for the gravity ow of refrigerant and absorbent raised by the vaporl liquid-lift and providing liquid columns between the shell and liquid heat exchanger.`

3. A self-contained vacuum type absorption refrigeration apparatus comprising a frame havinga base and spaced upright stanchions with saddlesat `their upper ends, a 'shell mounted on the saddles above the base and havingbrackets at its top and an evaporator and absorber therein, a condenser supported on the brackets at the top of the shell,`a generator mounted on the base and having a vapor liquid-lift projecting upwardly above the shell lat one end thereof, a centrifugal'separator connected between the upper end of the generator and condenser and comprising a horizontal shell having means therein for directing vapor in a helical path to cause liquid to be thrown outwardly by centrifugal force, a liquid heat exchanger mounted on the base of the frame, and conduits connecting the elements for the gravity ilow of refrigerant and absorbent raised by the vapor liquid-lift and providing liquid columns between the shell and liquid heat exchanger.

4. A self-contained vacuum type absorption refrigeration apparatus comprising a frame having a base and spaced upright stanchions with saddles at their upper ends, a shell mounted on the saddles above the base and having brackets at its top and an evaporator and absorber therein, a condenser supported on the brackets at the top ofthe shell, a generator mounted on the base and having a vapor liquid-lift projecting upwardly above the shell at one end thereof, a centrifugal separator extending horizontally between the upper end of the vapor liquid-lift and condenser and supported thereby, a liquid heat exchanger mounted on the base of the frame, a leveling vessel between the liquid heat exchanger and vapor liquid lift and supported by` the` stanchions of the frame, and conduits connecting the elements for the gravity iiow of refrigerant and absorbent raised by the vapor liquidlift and providing columns between the shell and liquid heat exchanger.

5. A self-contained vacuum type absorption refrigeration apparatus comprising a frame having a base and spaced upright stanchions with saddles at their upper ends, a shell mounted on the saddles above the base and having brackets at its top and an evaporator and absorber therein, a condenser supported on the brackets at the top of the shell, a centrifugal separator connected between the upper end of the vapor liquid- 10 lift and condenser and supported thereby, a liquid heat exchanger mounted on the base and having inner and outer passages extending lengthwise of the base at an acute angle thereto, and conduits connecting the elements for the gravity flow of refrigerant and absorbent raised by the vapor liquid-lift and providing liquid columns between the condenser and shell and between the shell and liquid heat exchanger.

6. A self-contained vacuum type absorption refrigeration apparatus comprising a frame having a base and spaced upright stanchions with saddles at their upper ends, a shell mounted on the saddles above the base and having brackets at its top and an evaporator and absorber therein, a condenser supported on the brackets at the top of the shell, a generator mounted on the base and having a vapor liquid-lift projecting upwardly above the shell at one end thereof, a separating chamber connected between the upper end of the vapor liquid-lift and condenser, a flash chamber mounted on the top of the shell, a jacket enclosing the flash chamber in spaced relation thereto to provide an insulating space therebetween, a liquid heat exchanger mounted on the base of the frame below the shell, conduits connecting the elements for the gravity Ilow of refrigerant and absorbent raised b'y the vapor liquid-lift and providing liquid columns between the condenser and shell and between the shell and liquid heat exchanger, and said ,jacket enclosing the flash chamber being connected to the system to produce a vacuum therein.

`7. In a vacuum type absorption refrigeration system, a generator, a condenser, an evaporator, an absorber, a combined flash chamber and gas storage element comprising two Vessels arranged one within the other in spaced relation, a device through which refrigerant flows from the condenser to the evaporator for maintaining a difference in pressure, conduits interconnecting the elements to provide paths of flow for refrigerant and absorbent, the conduit between the condenser and evaporator comprising a pipe connecting the pressure maintaining device to the inner ash chamber vessel, connecting means extending through the outer storage vessel to deliver a liquid and vapor refrigerant from the flash chamber vessel to the evaporator, means for purging non-condensable gases from the refrigeration system, and a riser tube extending above the highest level to which liquid can rise at the pressure in the refrigeration system and connected between the purge device and outer gas storage vessel to store gas and provide an insulating layer of low pressure gases around the flash chamber.

8. In a vacuum type absorption refrigeration system, a generator, a condenser, an evaporator, an absorber, a combined flash chamber and gas storage element comprising two vessels arranged one within the other in spaced relation, conduits interconnecting the elements to provide paths of iiow for refrigerant and absorbent, the conduit between the condenser and evaporator comprising a U-tube and the inner flash chamber vessel, a liquid pipe extending from the bottom of the inner flash chamber vessel through the outer storage vessel to the evaporator, a vapor pipe extending from above the bottom of the inner flash chamber vessel through the outer vessel to the evaporator, means for purging non-condensable gases from the refrigeration system, and a riser pipe extending above the highest level to which liquid can rise at the pressure in the re- 11 frigeration system and connected between the purging means and outer gas storage vessel .to store gas and provide an insulating layerof low pressure gases around the flash chamber.

9. In a vacuum type absorption refrigeration system, a Vapor liquid-lift for raising liquid b5 vapors expelled therefrom, and a Vcentrifugal separator at the upper end of Said lift for separating the liquid from the vapor, said centrifugal separator having a horizontally arranged cylindrical casing connected tangentiall'y to the lift and having bailies therein for directing the vapor in a helical path to cause liquid Ato be thrown outwardly against the wall of the casing by centrifugal force as the vapor flows therethrough.

10. In a Vacuum type absorption refrigeration system, an upright vapor liquid-lift for raising liquid by vapor expelled therefrom, a condenser above the vapor liquid lift, a centrifugal separator having a laterally extending casing, the upper end of the vapor liquid-lift being connected tangentially to the side of the casing at one end and the opposite end of the casing being connected to the condenser, and bafes in the casing forming a plurality of helical passages for 'directing the vapor in helical paths to cause liquid to be thrown outwardly against the wall of the casing by centrifugal force as the vapor ows from the upper end of the lift toward the condenser.

11. In a vacuum type absorption refrigeration system, an upright vapor liquid-lift for raising liquid by vapor expelled therefrom, a condenser above the upper end of the lift, a centrifugal 12 separator having a cylindrical lvessel extending laterally between .the vapor liquid lift and con- -denser,"the upper Yend of the lift being connected tangential-1y to the cyllindr-ical vessel at one end and the `opposite end of the vessel being Ycon nected to the condenser, an axial rod :extending longitudinally lof the cylindrical vessel, :a plu- .rality of Vdiscs mounted on the rod and having radial slots to provide blades twisted at an angle to :the plane of the .discs, the trailing :edge of each blade being aligned lwith the leading ,edge of a blade on the next adjacent disc to form a plurality of helical passages, yand said helical passages .directing the vapor to .cause it to flow in helical paths at high velocity and expel liquid therefrom by centrifugal force.

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